1. Field
The invention relates to infrared night vision systems for aircraft, particularly systems for helicopters.
2. Prior Art
Night operations with low flying covert aircraft like helicopters is possible with an Army developed night goggle system Aviators Night Vision Imaging System (ANVIS). The goggles amplify any visible light present due to the moon or stars and covert ambient infrared light to visible light. The longer wavelengths of infrared are particularly useful in fog and haze and in locating ground features by their temperature differentials. In certain cases visibility can be enhanced using infrared illuminators, since these are not visible to the naked eye. Usually an aviator wearing the above goggles can see obstacles well enough to avoid them, however, exceptions do occur. Featureless, low contrast terrain, such as desert sand dunes, can be such an exception. Under certain conditions of weather and natural illumination rising terrain features are indistinguishable causing a pilot to inadvertently fly into the terrain. While the use of active infrared devices is normally avoided on military helicopters, limited use to avoid loss of an airship is considered warranted in this circumstance. An object of the present invention is, therefore, to provide a narrow beam, minimum radiation, active, infrared (IR) obstacle avoidance device for use on terrains of the type indicated above.